SYSTEMS AND METHODS FOR MONITORING ENDOLUMINAL VALVE FORMATION
The invention generally relates to systems for imaging and monitoring endoluminal valve formation. In certain aspects, a system of the invention includes: an elongate body defining a lumen and an exit port located on a side of the elongate body, wherein the side of the elongate body is configured to engage with a vessel wall; a tissue dissection probe disposed within the lumen, and configured to extend out of the exit port and into the vessel wall in order to form an intramural space in the vessel wall; and an imaging element located on the tissue dissection probe.
This application claims the benefit of and priority to U.S. Provisional No. 61/880,532, filed Sep. 20, 2013, which is incorporated by reference herein.
TECHNICAL FIELDThis application relates generally to systems and methods for monitoring endoluminal valve formation.
BACKGROUNDThe venous system returns blood to the heart from the rest of the body. In healthy individuals, natural valves within veins permit blood flow in a substantially unidirectional manner along the length of the vessels. These one-way valves keep blood flowing toward the heart, against the force of gravity while preventing backflow.
Venous insufficiency is a condition in which the flow of blood through the veins is impaired, typically due to valve malfunction. When a valve malfunctions, blood may backflow into an extremity, such as a leg, causing blood pooling and distention. The pooling of blood caused by venous insufficiency leads to increased pressure or hypertension within the veins. The symptoms associated therewith include pain, swelling, and ulcers in the affected extremity. Elevation of the feet and compression stockings can relieve some symptoms, but do not treat the underlying disease. Untreated, the disease can impact the ability of individuals to maintain their normal lifestyle.
In order to treat venous insufficiency, a number of surgical procedures have been employed to improve or replace the native valve, including the implantation of prosthetic valves. A prosthetic valve is designed to mimic a natural valve in order to regain unidirectional blood flow within a vein. However, prosthetic valves are prone to high failure rates and biocompatibility issues. Due to these issues, implantation of a prosthetic valve is typically a last resort. As an alternative to prosthetic valves, other surgical procedures are being explored to create an autologous valve formed from an intimal tissue flap of a vessel wall. In order to create an autologous valve, an intimal tissue flap is created within a vessel wall, and then secured within the vessel such that the tissue flap mimics the function of a native valve. While lacking the risk of biocompatibility associated with prosthetic valves, autologous valve formation is a complex surgery that includes the inherent risk of tearing or puncturing the vessel wall. As such, there is a need for improving the systems and methods used to form valves in veins.
SUMMARYThe invention recognizes that current autologous valve formation procedures are limited because prior art valve formation devices do not allow visualization of the procedure within the lumen. Without visualization, the risk of puncturing the vessel or tearing the vessel wall is increased. Systems and methods of the invention reduce risk associated with autologous valve formation by providing systems that incorporate imaging with a catheter and/or a dissection probe used to form the intimal tissue flap. Such systems allow an operator to visualize the intimal flap and surrounding vessel surfaces while the intimal flap is being formed. In addition, systems of the invention may also include pressure and flow sensors that alert the operator of abnormal pressure/flow changes within the vessel during the autologous valve formation procedure. The abnormal pressure/flow changes may signify undesirable vessel puncture.
Systems of the invention include a support catheter and a tissue dissection probe (also referred to as puncture members) that extends out of the support catheter and into a vessel wall. Once disposed within the vessel wall, the tissue dissection probe is able to separate an inner tissue layer from the vessel wall to form a tissue flap. The tissue dissection probe may eject hydro-dissection fluid into the intramural space of the vessel wall to separate the tissue layers and thereby form the tissue flap. In particular embodiments, the tissue dissection probe also forms a pouch within the intramural space of the vessel wall using an expansion member. The expansion member forms a tissue flap of a certain shape ideal for valve creation. The support catheter, the tissue dissection probe, or both may include an imaging sensor, a functional measurement sensor, or a combination thereof.
The catheter systems of the invention, equipped with imaging elements, functional measurement sensors or both, can advantageously provide for 1) real-time imaging of intraluminal surfaces to detect a location of interest, 2) forming an intimal tissue flap within a vessel wall at the location of interest, 3) forming an endoluminal valve with the intimal tissue flap 3) real-time imaging of the location of interest (e.g. various vessel surfaces) before, during, and after the endoluminal procedure, and 4) real-time measurement of function parameters (such as pressure, flow, and temperature) before, during, and after the endoluminal valve formation procedure.
As discussed, the systems of the invention may include one or more imaging elements. Imaging elements of the invention may be a forward-looking imaging element, side-looking element, or combination of the two. Suitable imaging elements include, for example, ultrasound transducers and photoacoustic transducers. In addition, systems of the invention may include one or more functional measurement sensors. Functional measurement sensors include pressure sensors, flow sensors, temperature sensors, or combinations thereof. In one embodiment, the imaging element is placed on a distal portion of the support catheter. In another embodiment, the imaging element is placed on a distal portion of a dissection probe that enters the intramural space of a vessel wall. The imaging element of the dissection probe may be placed on or beneath an expansion member used to create a pocket within the vessel wall. Likewise, a functional measurement sensor may be placed on a distal portion of the support catheter or on a distal portion of a tissue dissection probe.
According to certain aspects, systems of the invention include at least two expandable members coupled to a support catheter so that the expansion members can stabilize the support catheter within the vessel during the endoluminal valve formation procedure. The expansion members provide bipod support while pressing the side of the support catheter where the tissue dissection device is deployed against the vessel wall. In this manner, the tissue dissection device is deployable into the vessel wall from the support catheter in a controlled manner without risk of unwanted movement.
The present invention generally relates to catheter systems for forming endoluminal valves with imaging capabilities, functional measurement capabilities, or both. The catheter systems of the invention for forming endoluminal valves are also referred to herein as tissue dissection assemblies. The catheter systems of the invention may provide for 1) real-time imaging of intraluminal surfaces to detect a location of interest, 2) forming a tissue flap within a vessel wall at the location of interest, 3) forming an endoluminal valve with the tissue flap 3) real-time imaging of the location of interest (e.g. various vessel surfaces) before, during, and after the endoluminal procedure, and 4) real-time measurement of function parameters (such as pressure, flow, and temperature) before, during, and after the endoluminal procedure.
Typically, catheter systems of the invention include a stabilizing/support catheter and one or more puncture members (as referred to as tissue dissection probes) configured to extend out of the stabilizing catheter and into a vessel wall. As used in this specification, the term support catheter or similar terms refer to any device that provides a conduit, channel, or lumen for housing and/or delivering a component or a substance. The support catheter serves as a platform to support other device components, such as one or more puncture members, which can be inserted percutaneously into bodily lumen(s). For example, once the support catheter is positioned at a location for flap formation, the puncture member is extended into a vessel wall. When disposed within the vessel wall, the puncture member is configured to separate a tissue flap from a tissue layer of the vessel wall without puncturing the vessel wall. The support catheter, the one or more puncture members, or combinations thereof may include an imaging sensor, functional measurement sensor or combination thereof. For example, in one embodiment, the support catheter may include an imaging element and the puncture member may include a functional measurement sensor. In another example, both the support catheter and the puncture member may include an imaging element and/or functional measurement sensor. In yet another example, only the support catheter or the puncture member includes the functional measurement sensor and/or the imaging element.
Imaging elements and functional measurement sensor are described in more detail hereinafter. Briefly, the imaging element may include, for example, an ultrasound transducer or photo-acoustic transducer. The functional measurement sensor may include a flow sensor, pressure sensor, and temperature sensor.
In certain embodiments, an imaging guidewire can be introduced into a lumen of the body to obtain real-time images of the vessel prior to introduction of the support catheter over the guidewire. The body lumens generally are lumens of the vasculature. The real-time images obtained may be used to locate a region or location of interest within a body lumen. Regions of interest are typical regions that are an ideal location for forming a valve within a vessel. For example, the location may be the ideal location to form a valve within the vessel for treating venous reflux. The devices and methods, however, are also suitable for forming tissue flaps and valves in other body lumens, such as the respiratory passages, the pancreatic system, the lymphatic system, and the like.
Systems and methods of the invention are designed to enter a body lumen and form an intramural space within a wall of the body lumen. Typically, the intramural space forms a tissue flap from the extending from the vessel wall. The tissue flap can then be secured to a vessel wall to form a valve. In accordance with embodiments for creating an intra-mural potential space, and access to that space, systems of the invention include a support catheter and one or more puncture elements. The puncture element may form an intra-mural space by, for example, injecting a hydrodissection fluid into the vessel wall, expanding an expansion member located on or formed as part of the puncture element, or by a combination of said injection/expansion. The various embodiments of the support catheter and puncture elements for creating an intramural space as well as methods for creating an intra-mural space are described hereinafter. In addition, concepts of the invention may be applied to prior art systems for forming endoluminal valves, such as those described in U.S. Publication Nos. 2011/0264125 and 2012/0289987, the entireties of which is incorporated by reference herein.
The following describes generally methods for creating an intramural space in a vessel wall using support catheters and puncture elements of the invention. In accordance with some embodiments, a method includes stabilizing a support catheter against vessel wall at a desired location to form an intramural space/tissue flap in the vessel wall. Once secured, a probe (e.g. puncture element) is advanced into the vessel wall a minimal amount. The probe then expels a pressurized hydrodissection agent (saline or saline with a contrast agent, or a hydrogel, or water for injection) from its distal tip to separate the intimal tissue layer from the medial tissue layer, or the medial layer from the adventitial layer, or a fibrosis layer from the intimal layer, or a sub-medial layer from another sub-medial layer, or a sub-adventitial layer from another sub-adventitial layer. This propagates distally from the distal end of the probe. In this way, a tissue pocket is formed without the need to further advance the probe into the wall, as long as sufficient flow is provided, and the pocket created is free from a significant leak at the top of the pocket (at probe entry), or from a hole leading into the lumen or extravascular space. In this way a fluid sealed pocket is formed with only one opening at the entry point. In some embodiments, a typical hydrodissection flow is between 0.25 cc/second and 3 cc/second. In other embodiments, a typical hydrodissection flow is between 0.5 cc/second and 2 cc/second. In other embodiments, a typical hydrodissection flow is between 0.75 cc/second and 1.25 cc/second. In addition or as an alternative to injecting hydrodissection fluid, once the probe is disposed within the vessel wall, an expandable member on the probe is expanded to form the intraluminal space.
In accordance with some embodiments, the support catheter 1600 is described to aid in the direction of advancement 1610 of a tissue dissection probe within the vessel wall 1620 by controlling the angle of the vessel wall 1620. In one embodiment, a sufficiently stiff, flat surface 1640 along the distal portion 1660 of the support catheter 1600 exists to ensure the vessel wall 1620 does not bend inward toward the lumen, and thus preventing the advancement direction of the tissue dissection probe 1610 from pointing outward through the adventitia (
In certain embodiments, the stiff, flat surface 1640 of the distal portion 1660 of the support catheter 1600 is sufficiently stiff to resist bending about the x and y axis (as depicted). This way, if the vessel in which the device is implanted takes a tortuous path, the distal portion 1660 resists bending along with the vessel, which allows advancement of a puncture element or tissue dissection probe to be ensured to maintain sufficiently parallel trajectory 1610 (along the z axis) and to maintain position within the center of the flat surface 1640 (not meandering off the side of the flat surface entirely along the positive or negative x axis). This can be done by using inherently stiff materials for the entire support catheter 1600 or exclusively in the distal portion 1660 of the support catheter 1660. In some embodiments, the distal portion 1660 that must have sufficient stiffness can be defined by the portion spanning at least 4 cm proximal to the exit port 1670 of the support catheter, and spanning at least 4 cm distal the exit port 1670. In some embodiments, the distal portion 1660 that must have sufficient stiffness can be defined by the portion spanning at least 2 cm proximal to the exit port 1670 of the support catheter, and spanning at least 2 cm distal the exit port 1670. In some embodiments, the distal portion 1660 that must have sufficient stiffness can be defined by the portion spanning at least 1.25 cm proximal to the exit port 1670 of the support mechanism, and spanning at least 1.25 cm distal the exit port 1670. In some embodiments sufficiently stiff is defined as less than 4 mm of deformation if a 0.5 lb force is applied along a 6 cm lever arm. In some embodiments sufficiently stiff is defined as resistance to 2 mm of deformation if a 0.5 lb force is applied along a 6 cm lever arm. In some embodiments sufficiently stiff is defined as resistance to 1 mm of deformation if a 0.5 lb force is applied along a 6 cm lever arm. In some embodiments sufficiently stiff is defined as resistance to 0.25 mm of deformation if a 0.5 lb force is applied along a 6 cm lever arm.
Typically, the support catheter 1600 includes an expansion member 1685 that presses the support catheter 1600 against the vessel wall such that the puncture element can enter the vessel wall in a controlled manner (as shown in
The distal portion 1660 must be stiff enough to resist bending in about any axis (by more than 2 mm over a 6 cm lever arm) along the entire length of the expanded expansion mechanism while the mechanism is expanded. For example, if a balloon is expanded causing even a curved vessel to straighten out and causing the vessel wall to conform along the distal portion of the support mechanism, the distal portion must be stiff enough to resist bending as a result of the tensioned wall, for the entire axial length of the expanded balloon.
The puncture element 1680 may include an imaging element 1663, a functional measurement sensor 1664, an expandable member, or combination thereof. As shown in
In certain embodiments, the puncture element 1680 is considered a dissection probe itself. In other embodiments, the puncture element 1680, depicted in
In other embodiments of this kind, a controlled hydrodissection mechanism 230 is used to create the pouch (see
The larger the intramural space formed within the vessel wall, the larger the resulting tissue flap will be for forming an endoluminal valve within the vessel. After a valve pocket/valve flap has been created it is necessary to secure the valve flap to form the actual valve. Securing the valve flap also prevents it from re-adhering to the wall and, depending on the securement, controls hemodynamic properties associated with flow through the valve and the mechanics of the valve itself.
The support catheter 2 also includes an angling mechanism 11. In this embodiment, the angling mechanism 11 takes the form of a wire 12 connected with a mechanical bond 13 to the distal-most end of the internal lumen 6 of the conduit 2. In this embodiment, the angling mechanism 11 extends through the internal lumen 6 and past the proximal end 4 of the conduit 2. In this embodiment, the stiffness of the elongated tube 3 is lower at the distal end than at the proximal end so that when the wire 12 of the angling mechanism 11 is put into tension by the user at the proximal end, the elongated tube forms a curvature 14 near its distal end. Anyone skilled in the art of steerable catheters should understand how this mechanism can be used to create a curvature for the elongated tube 3. This curvature will allow tools to be passed through the sideway facing exit port 7 to take a non-parallel angle relative to the lumen wall, facilitating autologous valve creation.
In the illustrated embodiments, the support catheter 2 also includes a wall-tensioning mechanism 15. As used in this specification, the term “wall-tensioning mechanism” or similar terms refer to any device that is configured to apply tension at a wall of a vessel. The wall-tensioning mechanism 15 includes a sideway-facing, inflatable, compliant balloon 16 of nearly cylindrical shape. The balloon 16 is coupled to the elongated tube 3 near the distal end 5 of the elongated tube 3. The balloon is in fluid communication with an inflation lumen 17, which communicates with an inflation port at the proximal end 4 of the elongated tube 3. The inflatable balloon 16 can be inflated to multiple diameters depending on the quantity and pressure of inflation fluid supplied through the inflation lumen 17.
As shown in
As depicted in
In the illustrated embodiments, the sub-intimal access member 18 includes an elongated member 19 with a proximal end 20, a guide member 100 having a closed blunt distal end 21, an internal lumen 22, and a tissue engagement mechanism 23 extending from the elongated tube 19 at a location a small distance (e.g. 2 mm-8 mm) proximal to the closed blunt distal end 21. In this depiction, the tissue engagement mechanism 23 includes a tubular structure 101 with a lumen 24 in fluid communication with the main lumen 22 of the sub-intimal access member 18. There is therefore fluid communication from the proximal end 20 of the sub-intimal access member 18 through the entire length of the main lumen 22 of the sub-intimal access probe 18, into the lumen 24 of the tissue engagement mechanism 23, terminating distally at a forward facing exit port 25. In some embodiments, the tissue engagement mechanism 23 forms a relative angle with the elongated tube 19 of the sub-intimal access probe 18. The intersection of the tissue engagement mechanism 23 and the body of the elongated tube 19 creates a bottoming-out mechanism 26, in the form of an elbow joint. In some embodiments, the tissue engagement mechanism 23 may be attached to the elongated tube 19. For example, the tissue engagement mechanism 23 may be a part of the elongated tube 19. The tissue engagement mechanism 23 has a sharpened tip 27 at the distal end of the tubular structure 101, to facilitate penetration of an interior wall of a blood vessel. The sharpened tip 27 of the tubular structure 101 is proximal to the blunt end 21 of the guide member 100. The tubular structure 101 runs substantially parallel to the body of the guide member 100 such that a layer of skin tissue of the vessel wall fits between the guide member 100 and tubular structure 101 when the tubular structure 101 is deployed into a vessel wall. The angular orientation of the bevel of the sharpened tip 27 is such that the distal most point of the bevel is oriented furthest away from a longitudinal axis 102 of the sub-intimal access probe 18. In particular, the distal profile of the tip 27 tapers proximally from a first side 104 to a second side 106, wherein the first side 104 is further away from the axis 102 than the second side 106. Such configuration is advantageous because it allows the tip 27 to penetrate into the vessel wall more easily.
The sub-intimal access probe 18 also includes a tissue layer separation mechanism 28. As used in this specification, the term “tissue layer separation mechanism” or similar terms refer to any mechanism that is capable of separating tissue (e.g., dissecting tissue). The tissue layer separation mechanism 28 includes a pressurized source of fluoroscopic contrast agent 10, and a tissue layer separation actuator 29.
In some embodiments, the agent 10 may be a contrast agent, which may be imaged using an imaging device, such as a fluoroscopic device. This allows the position of the device 18 to be determined, and the fluid path of the agent 10 to be visualized during delivery of the agent 10. This also allows the progress of the separation of the tissue layers in the vessel to be monitored. The distal tip 21 of the guide member 100 is configured to be placed on a surface at an interior wall of the vessel to thereby guide the positioning (e.g., orientation) of the tip 27 relative to the vessel wall surface. In some cases, pressure may be applied to the vessel wall surface by pushing the blunt tip 21 distally, which will apply tension to the wall surface, and/or change an orientation of the wall surface—either or both of which will allow the tip 27 to more easily penetrate into the wall of the vessel.
The distal tip 21 of the guide member 100 is configured to be placed on a surface at an interior wall of the vessel to thereby guide the positioning (e.g., orientation) of the tip 27 relative to the vessel wall surface. In some cases, pressure may be applied to the vessel wall surface by pushing the blunt tip 21 distally, which will apply tension to the wall surface, and/or change an orientation of the wall surface—either or both of which will allow the tip 27 to more easily penetrate into the wall of the vessel.
In some embodiments, the tissue layer separation mechanism 28 is configured to dissect tissue in the wall of the vessel to create a pocket inside the wall of the vessel having a size that is sufficient to form a flap at the vessel wall. In such cases, the fluid stream 30 functions as a sub-intimal pocket probe. In other embodiments, the tissue layer separation mechanism 28 is configured to deliver the fluid stream 30 to create an initial lumen in the wall of the vessel, and another device may be placed in the lumen to expand the size of the lumen to create a pocket that is large enough to form a flap at the vessel wall.
According to certain embodiments and as shown at least in
As shown in 11B, the balloon 28 includes a first end 1701 and a second end 1702. When expanded, the first end 1701 defines a larger volume than the second end 1702. With this configuration, the balloon 28 forms a cone or triangle shape. In such configurations, the balloon 28 may define a conical volume. The volume of the balloon 28 at the first end 1701 is larger than the volume at the second end 1701 in order to create a gradual tissue flap. The gradual tissue flap prevents excessive tension where the tissue flap merges with the vessel wall.
In some embodiments, the sub-intimal pocket mechanism 32 may optionally further include a channel for delivering a valve securement mechanism, wherein the valve securement mechanism is configured to secure a flap against a wall of a vessel.
Because a fluoroscopic contrast agent 10 is used in tissue layer separation in this embodiment, the user will have the opportunity to visualize the effect of the fluid delivery on the tissue using fluoroscopic visualization techniques. In particular, through fluoroscopic visualization technique, the user may view the progress of the tissue dissection within the wall of the vessel. The fluoroscopic visualization technique also allows a user to determine if the dissection plane 31 is getting too close to the exterior surface of the vessel wall. In such cases, the user may determine that there is a potential that the vessel wall may be punctured (by the fluid) therethrough, and may stop the process. Additionally, this visualization technique allows the user to evaluate the depth and shape of the newly created inter-layer plane 31 to determine if the tissue layer separation mechanism 28 needs to be actuated again. This process may be repeated indefinitely until a proper tissue layer separation has occurred, which allows for continuation of the procedure.
After the valve 67 is created, the user may visualize the effect of autologous valve creation using fluoroscopic visualization techniques. Contrast agent 10 can be injected through the forward facing exit port 25 of the pocket-creation mechanism 32 (or through another fluid delivery device) at any appropriate time during the procedure. This tool will be especially useful after valve creation has been accomplished. In this case, the user may first deflate the pocket creation balloon 38 to facilitate placement of the forward facing exit port 25 in the newly created sub-intimal pocket 64. Standard techniques—including manual pumping of the calf muscle—can be used to force blood flow through the autologous valve 67 for evaluation. Once visualization confirms that autologous valve 67 is functioning properly, the device is removed from the bodily lumen.
Systems and methods of the invention may include one or more expandable members (also called expansion elements). Typically, the expandable members are balloons. Balloons suitable for use in the invention may include any material that exhibits suitable strength and elasticity. Suitable materials may include polyvinyl chloride (PVC), cross-linked polyethylene (PET), nylon, or other polymers. In some embodiments, the balloon includes artificial muscle (electro-active polymer). Electro-active polymers exhibit an ability to change dimension in response to electric stimulation. The change may be driven by electric field E or by ions. Exemplary polymers that respond to electric fields include ferroelectric polymers (commonly known polyvinylidene fluoride and nylon 11, for example), dielectric EAPs, electro-restrictive polymers such as the electro-restrictive graft elastomers and electro-viscoelastic elastomers, and liquid crystal elastomer composite materials. Ion responsive polymers include ionic polymer gels, ionomeric polymer-metal composites, conductive polymers and carbon nanotube composites. Common polymer materials such as polyethylene, polystyrene, polypropylene, etc., can be made conductive by including conductive fillers to the polymer to create current-carrying paths. Many such polymers are thermoplastic, but thermosetting materials such as epoxies, may also be employed. Suitable conductive fillers include metals and carbon, e.g., in the form of sputter coatings. Electro-active polymers are discussed in U.S. Pat. No. 7,951,186; U.S. Pat. No. 7,777,399; and U.S. Pub. 2007/0247033, the contents of each of which are incorporated by reference. Balloons can be inflated using any technique known in the art, typically by introducing a fluid or gaseous element into the balloon.
According to certain embodiments, the components of the endoluminal valve catheter systems of the invention include one or more imaging elements. Imaging elements of any one component may different from any other component. For example, the imaging element of a support catheter may be different from the puncture member, access probe, or pocket probe. Imaging elements suitable for use with components of the endoluminal valve catheter systems of the invention are described hereinafter. Typically, the imaging element is a component of an imaging assembly. Any imaging assembly may be used with devices and methods of the invention, such as optical-acoustic imaging apparatus, intravascular ultrasound (IVUS) or optical coherence tomography (OCT). The imaging element may be a forward looking imaging element or a side-looking imaging element. The imaging element is used to send and receive signals to and from the imaging surface that form the imaging data. All of the imaging elements described hereinafter may be coupled to a signal line that provide power and allow data transmission to and from the imaging element. Typically, the signal line is coupled to an imaging system, such as a computer. The signal lines may be routed through lumens already existing in components of the endoluminal valve catheter system. Alternatively, the components can be specifically designed with lumens, in which the one or more signal lines are routed therethrough. The creation of multi-lumen catheter components is known in the art.
The imaging assembly may be an intravascular ultrasound (IVUS) imaging assembly. IVUS uses an ultrasound probe attached at the distal end. The ultrasound probe is typically an array of circumferentially positioned transducers. However, it is also envisioned that the imaging element may be a rotating transducer. For example, when the puncture element is coupled to a rotary drive shaft to enable rotation of the puncture element, the imaging element may be a rotating transducer. The proximal end of the catheter is attached to computerized ultrasound equipment. The IVUS imaging element (i.e. ultrasound probe) includes transducers that image the tissue with ultrasound energy (e.g., 20-50 MHz range) and image collectors that collect the returned energy (echo) to create an intravascular image. The imaging transducers and imaging collectors are coupled to signal lines that run through the length of the catheter and couple to the computerized ultrasound equipment.
IVUS imaging assemblies produce ultrasound energy and receive echoes from which real time ultrasound images of a thin section of the blood vessel are produced. The imaging transducers of the imaging element are constructed from piezoelectric components that produce sound energy at 20-50 MHz. The image collectors of the imaging element comprise separate piezoelectric elements that receive the ultrasound energy that is reflected from the vasculature. Alternative embodiments of imaging assembly may use the same piezoelectric components to produce and receive the ultrasonic energy, for example, by using pulsed ultrasound. That is, the imaging transducer and the imaging collectors are the same. Another alternative embodiment may incorporate ultrasound absorbing materials and ultrasound lenses to increase signal to noise.
IVUS data is typically gathered in segments where each segment represents an angular portion of an IVUS image. Thus, it takes a plurality of segments (or a set of IVUS data) to image an entire cross-section of a vascular object. Furthermore, multiple sets of IVUS data are typically gathered from multiple locations within a vascular object (e.g., by moving the transducer linearly through the vessel). These multiple sets of data can then be used to create a plurality of two-dimensional (2D) images or one three-dimensional (3D) image.
IVUS imaging assemblies and processing of IVUS data are described in further detail in, for example, Yock, U.S. Pat. Nos. 4,794,931, 5,000,185, and 5,313,949; Sieben et al., U.S. Pat. Nos. 5,243,988, and 5,353,798; Crowley et al., U.S. Pat. No. 4,951,677; Pomeranz, U.S. Pat. No. 5,095,911, Griffith et al., U.S. Pat. No. 4,841,977, Maroney et al., U.S. Pat. No. 5,373,849, Born et al., U.S. Pat. No. 5,176,141, Lancee et al., U.S. Pat. No. 5,240,003, Lancee et al., U.S. Pat. No. 5,375,602, Gardineer et at., U.S. Pat. No. 5,373,845, Seward et al., Mayo Clinic Proceedings 71(7):629-635 (1996), Packer et al., Cardiostim Conference 833 (1994), “Ultrasound Cardioscopy,” Eur. J.C.P.E. 4(2):193 (June 1994), Eberle et al., U.S. Pat. No. 5,453,575, Eberle et al., U.S. Pat. No. 5,368,037, Eberle et at., U.S. Pat. No. 5,183,048, Eberle et al., U.S. Pat. No. 5,167,233, Eberle et at., U.S. Pat. No. 4,917,097, Eberle et at., U.S. Pat. No. 5,135,486, U.S. Pub. 2009/0284332; U.S. Pub. 2009/0195514 A1; U.S. Pub. 2007/0232933; and U.S. Pub. 2005/0249391 and other references well known in the art relating to intraluminal ultrasound devices and modalities.
In other embodiments, the imaging assembly may be an optical coherence tomography imaging assembly. OCT is a medical imaging methodology using a miniaturized near infrared light-emitting probe. As an optical signal acquisition and processing method, it captures micrometer-resolution, three-dimensional images from within optical scattering media (e.g., biological tissue). Recently it has also begun to be used in interventional cardiology to help diagnose coronary artery disease. OCT allows the application of interferometric technology to see from inside, for example, blood vessels, visualizing the endothelium (inner wall) of blood vessels in living individuals.
OCT systems and methods are generally described in Castella et al., U.S. Pat. No. 8,108,030, Milner et al., U.S. Patent Application Publication No. 2011/0152771, Condit et al., U.S. Patent Application Publication No. 2010/0220334, Castella et al., U.S. Patent Application Publication No. 2009/0043191, Milner et al., U.S. Patent Application Publication No. 2008/0291463, and Kemp, N., U.S. Patent Application Publication No. 2008/0180683, the content of each of which is incorporated by reference in its entirety.
In OCT, a light source delivers a beam of light to an imaging device to image target tissue. Light sources can include pulsating light sources or lasers, continuous wave light sources or lasers, tunable lasers, broadband light source, or multiple tunable laser. Within the light source is an optical amplifier and a tunable filter that allows a user to select a wavelength of light to be amplified. Wavelengths commonly used in medical applications include near-infrared light, for example between about 800 nm and about 1700 nm.
Aspects of the invention may obtain imaging data from an OCT system, including OCT systems that operate in either the time domain or frequency (high definition) domain. Basic differences between time-domain OCT and frequency-domain OCT is that in time-domain OCT, the scanning mechanism is a movable mirror, which is scanned as a function of time during the image acquisition. However, in the frequency-domain OCT, there are no moving parts and the image is scanned as a function of frequency or wavelength.
In time-domain OCT systems an interference spectrum is obtained by moving the scanning mechanism, such as a reference mirror, longitudinally to change the reference path and match multiple optical paths due to reflections within the sample. The signal giving the reflectivity is sampled over time, and light traveling at a specific distance creates interference in the detector. Moving the scanning mechanism laterally (or rotationally) across the sample produces two-dimensional and three-dimensional images.
In frequency domain OCT, a light source capable of emitting a range of optical frequencies excites an interferometer, the interferometer combines the light returned from a sample with a reference beam of light from the same source, and the intensity of the combined light is recorded as a function of optical frequency to form an interference spectrum. A Fourier transform of the interference spectrum provides the reflectance distribution along the depth within the sample.
Several methods of frequency domain OCT are described in the literature. In spectral-domain OCT (SD-OCT), also sometimes called “Spectral Radar” (Optics letters, Vol. 21, No. 14 (1996) 1087-1089), a grating or prism or other means is used to disperse the output of the interferometer into its optical frequency components. The intensities of these separated components are measured using an array of optical detectors, each detector receiving an optical frequency or a fractional range of optical frequencies. The set of measurements from these optical detectors forms an interference spectrum (Smith, L. M. and C. C. Dobson, Applied Optics 28: 3339-3342), wherein the distance to a scatterer is determined by the wavelength dependent fringe spacing within the power spectrum. SD-OCT has enabled the determination of distance and scattering intensity of multiple scatters lying along the illumination axis by analyzing a single the exposure of an array of optical detectors so that no scanning in depth is necessary. Typically the light source emits a broad range of optical frequencies simultaneously.
Alternatively, in swept-source OCT, the interference spectrum is recorded by using a source with adjustable optical frequency, with the optical frequency of the source swept through a range of optical frequencies, and recording the interfered light intensity as a function of time during the sweep. An example of swept-source OCT is described in U.S. Pat. No. 5,321,501.
Generally, time domain systems and frequency domain systems can further vary in type based upon the optical layout of the systems: common beam path systems and differential beam path systems. A common beam path system sends all produced light through a single optical fiber to generate a reference signal and a sample signal whereas a differential beam path system splits the produced light such that a portion of the light is directed to the sample and the other portion is directed to a reference surface. Common beam path systems are described in U.S. Pat. No. 7,999,938; U.S. Pat. No. 7,995,210; and U.S. Pat. No. 7,787,127 and differential beam path systems are described in U.S. Pat. No. 7,783,337; U.S. Pat. No. 6,134,003; and U.S. Pat. No. 6,421,164, the contents of each of which are incorporated by reference herein in its entirety.
In yet another embodiment, the imaging assembly is an optical-acoustic imaging apparatus. Optical-acoustic imaging apparatus include at least one imaging element to send and receive imaging signals. In one embodiment, the imaging element includes at least one acoustic-to-optical transducer. In certain embodiments, the acoustic-to-optical transducer is an Fiber Bragg Grating within an optical fiber. In addition, the imaging elements may include the optical fiber with one or more Fiber Bragg Gratings (acoustic-to-optical transducer) and one or more other transducers. The at least one other transducer may be used to generate the acoustic energy for imaging. Acoustic generating transducers can be electric-to-acoustic transducers or optical-to-acoustic transducers. The imaging elements suitable for use in devices of the invention are described in more detail below.
Fiber Bragg Gratings for imaging provides a means for measuring the interference between two paths taken by an optical beam. A partially-reflecting Fiber Bragg Grating is used to split the incident beam of light into two parts, in which one part of the beam travels along a path that is kept constant (constant path) and another part travels a path for detecting a change (change path). The paths are then combined to detect any interferences in the beam. If the paths are identical, then the two paths combine to form the original beam. If the paths are different, then the two parts will add or subtract from each other and form an interference. The Fiber Bragg Grating elements are thus able to sense a change wavelength between the constant path and the change path based on received ultrasound or acoustic energy. The detected optical signal interferences can be used to generate an image using any conventional means.
Exemplary optical-acoustic imaging assemblies are disclosed in more detail in U.S. Pat. Nos. 6,659,957 and 7,527,594, 7,245.789, 7447,388, 7,660,492, 8,059,923 and in U.S. Patent Publication Nos. 2008/0119739, 2010/0087732 and 2012/0108943.
In certain embodiments, an imaging element is disposed beneath or on a surface of an expansion member or balloon.
The imaging element may be a side-looking imaging element, a forward-looking imaging element, or combination thereof. Examples of forward-looking ultrasound assemblies are described in U.S. Pat. Nos. 7,736,317, 6,780,157, and 6,457,365, and in Yao Wang, Douglas N. Stephens, and Matthew O'Donnellie, “Optimizing the Beam Pattern of a Forward-Viewing Ring-Annular Ultrasoun Array for Intravascular Imaging”, Transactions on Ultrasonics, Rerroelectrics, and Frequency Control, vol. 49, no. 12, December 2002. Examples of forward-looking optical coherence tomography assemblies are described in U.S. Publication No. 2010/0220334, Fleming C. P., Wang H., Quan, K. J., and Rollins A. M., “Real-time monitoring of cardiac radio-frequency ablation lesion formation using an optical coherence tomography forward-imaging catheter.,” J. Biomed. Opt. 15, (3), 030516-030513 ((2010)), and Wang H, Kang W, Carrigan T, et al; In vivo intracardiac optical coherence tomography imaging through percutaneous access: toward image-guided radio-frequency ablation. J. Biomed. Opt. 0001; 16(11):110505-110505-3. doi:10.1117/1.3656966. In certain aspects, an imaging assembly includes both side-viewing and forward-looking capabilities. These imaging assemblies utilize different frequencies that permit the imaging assembly to isolate between forward looking imaging signals and side viewing imaging signals. For example, the imaging assembly is designed so that a side imaging port is mainly sensitive to side-viewing frequencies and a forward viewing imaging port is mainly sensitive to forward viewing frequencies. Example of this type of imaging element is described in U.S. Pat. Nos. 7,736,317, 6,780,157, and 6,457,365.
Functional measurement sensors suitable coupled to one or more components of endoluminal valve catheter systems of the invention include, for example, a pressure sensor, temperature sensors, flow sensor, or combination thereof.
A pressure sensor allows one to obtain pressure measurements within a body lumen. A particular benefit of pressure sensors is that pressure sensors allow one to measure of FFR in vessel. FFR is a comparison of the pressure within a vessel at positions prior to the stenosis and after the stenosis. The level of FFR determines the significance of the stenosis, which allows physicians to more accurately identify clinically relevant stenosis. For example, an FFR measurement above 0.80 indicates normal coronary blood flow and a non-significant stenosis. Another benefit is that a physician can measure the pressure before and after an intraluminal intervention procedure to determine the impact of the procedure.
A pressure sensor can be mounted on the distal portion of a flexible elongate member. In certain embodiments, the pressure sensor is positioned distal to the compressible and bendable coil segment of the elongate member. This allows the pressure sensor to move along with the along coil segment as bended and away from the longitudinal axis. The pressure sensor can be formed of a crystal semiconductor material having a recess therein and forming a diaphragm bordered by a rim. A reinforcing member is bonded to the crystal and reinforces the rim of the crystal and has a cavity therein underlying the diaphragm and exposed to the diaphragm. A resistor having opposite ends is carried by the crystal and has a portion thereof overlying a portion of the diaphragm. Electrical conductor wires can be connected to opposite ends of the resistor and extend within the flexible elongate member to the proximal portion of the flexible elongate member. Additional details of suitable pressure sensors that may be used with devices of the invention are described in U.S. Pat. No. 6,106,476. U.S. Pat. No. 6,106,476 also describes suitable methods for mounting the pressure sensor 104 within a sensor housing.
A flow sensor can be used to measure blood flow velocity within the vessel, which can be used to assess coronary flow reserve (CFR). The flow sensor can be, for example, an ultrasound transducer, a Doppler flow sensor or any other suitable flow sensor, disposed at or in close proximity to the distal tip of the guidewire. The ultrasound transducer may be any suitable transducer, and may be mounted in the distal end using any conventional method, including the manner described in U.S. Pat. Nos. 5,125,137, 6,551,250 and 5,873,835.
External imaging modality devices for use in methods and devices of the invention include, for example, X-ray angiography imaging, computed tomography imaging, and magnetic resonance imaging devices. Preferably, the imaging modality is computed tomography which does not require the use of a contrast, which may not enter the small vessels of the microvasculature or stenosis vessels in adequate amounts for proper imaging.
In some embodiments, a device of the invention includes an imaging assembly and obtains a three-dimensional data set through the operation of OCT, IVUS, or other imaging hardware. In addition, a device of the invention, according to certain embodiments, may include a functional measurement sensor that obtains data through operation of functional measurement hardware. The imaging hardware and functional measurement hardware may be the same or different. In some embodiments, a device of the invention is a computer device such as a laptop, desktop, or tablet computer, and obtains a three-dimensional data set by retrieving it from a tangible storage medium, such as a disk drive on a server using a network or as an email attachment.
Methods of the invention can be performed using software, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions can also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations (e.g., imaging apparatus in one room and host workstation in another, or in separate buildings, for example, with wireless or wired connections).
In some embodiments, a user interacts with a visual interface to view images from the imaging system. Input from a user (e.g., parameters or a selection) are received by a processor in an electronic device. The selection can be rendered into a visible display. An exemplary system including an electronic device is illustrated in
Processors suitable for the execution of computer program include, by way of example, both general and special purpose microprocessors, and any one or more processor of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, (e.g., EPROM, EEPROM, solid state drive (SSD), and flash memory devices); magnetic disks, (e.g., internal hard disks or removable disks); magneto-optical disks; and optical disks (e.g., CD and DVD disks). The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.
To provide for interaction with a user, the subject matter described herein can be implemented on a computer having an I/O device, e.g., a CRT, LCD, LED, or projection device for displaying information to the user and an input or output device such as a keyboard and a pointing device, (e.g., a mouse or a trackball), by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well. For example, feedback provided to the user can be any form of sensory feedback, (e.g., visual feedback, auditory feedback, or tactile feedback), and input from the user can be received in any form, including acoustic, speech, or tactile input.
The subject matter described herein can be implemented in a computing system that includes a back-end component (e.g., a data server 413), a middleware component (e.g., an application server), or a front-end component (e.g., a client computer 449 having a graphical user interface 454 or a web browser through which a user can interact with an implementation of the subject matter described herein), or any combination of such back-end, middleware, and front-end components. The components of the system can be interconnected through network 409 by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include cell network (e.g., 3G or 4G), a local area network (LAN), and a wide area network (WAN), e.g., the Internet.
The subject matter described herein can be implemented as one or more computer program products, such as one or more computer programs tangibly embodied in an information carrier (e.g., in a non-transitory computer-readable medium) for execution by, or to control the operation of, data processing apparatus (e.g., a programmable processor, a computer, or multiple computers). A computer program (also known as a program, software, software application, app, macro, or code) can be written in any form of programming language, including compiled or interpreted languages (e.g., C, C++, Perl), and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. Systems and methods of the invention can include instructions written in any suitable programming language known in the art, including, without limitation, C, C++, Perl, Java, ActiveX, HTML5, Visual Basic, or JavaScript.
A computer program does not necessarily correspond to a file. A program can be stored in a portion of file 417 that holds other programs or data, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub-programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.
A file can be a digital file, for example, stored on a hard drive, SSD, CD, or other tangible, non-transitory medium. A file can be sent from one device to another over network 409 (e.g., as packets being sent from a server to a client, for example, through a Network Interface Card, modem, wireless card, or similar).
Writing a file according to the invention involves transforming a tangible, non-transitory computer-readable medium, for example, by adding, removing, or rearranging particles (e.g., with a net charge or dipole moment into patterns of magnetization by read/write heads), the patterns then representing new collocations of information about objective physical phenomena desired by, and useful to, the user. In some embodiments, writing involves a physical transformation of material in tangible, non-transitory computer readable media (e.g., with certain optical properties so that optical read/write devices can then read the new and useful collocation of information, e.g., burning a CD-ROM). In some embodiments, writing a file includes transforming a physical flash memory apparatus such as NAND flash memory device and storing information by transforming physical elements in an array of memory cells made from floating-gate transistors. Methods of writing a file are well-known in the art and, for example, can be invoked manually or automatically by a program or by a save command from software or a write command from a programming language.
In addition, system and methods of the invention provide an implantable valve. The implantable valve is an artificial valve prosthesis designed to replace or supplement the function of incompetent valve. The valve prostheses of the invention are constructed so as to allow fluid flow in a first, antegrade, direction and to restrict fluid flow in a second, retrograde, direction.
Implantable valves of the invention are desirably adapted for deployment within a body lumen, and in particular embodiments, devices and systems of the invention are adapted for deployment within the venous system. Accordingly, preferred devices adapted are venous valves, for example, for percutaneous implantation within veins of the legs or feet to treat venous insufficiency. However, devices and systems of the present invention may be adapted for deployment within any tube-shaped body passage lumen that conducts fluid, including but not limited to blood vessels, such as those of the human vasculature system; billiary ducts; ureteral passages and the alimentary canal.
One aspect of the present invention provides a self-expanding or otherwise expandable artificial valve prosthesis for deployment within a bodily passageway, such as a vessel or duct of a patient. The prosthesis is typically delivered and implanted using well-known transcatheter techniques for self-expanding or otherwise expandable prostheses. The valve prosthesis is positioned so as to allow antegrade fluid flow and to restrict retrograde fluid flow. Antegrade fluid flow travels from the distal (upstream) end of the prosthesis to the proximal (downstream) end of the prosthesis, the latter being located closest to the heart in a venous valve when placed within the lower extremities of a patient. Retrograde fluid flow travels from the proximal (downstream) end of the prosthesis to the distal (upstream) end of the prosthesis
The implantable valves of the invention may be delivered into a body lumen using a delivery catheter. Delivery catheters are known in the art. Exemplary delivery catheters include those described in U.S. Pat. Nos. 8,167,932 8,021,420, 8,475,522 and 8,353,945 as well as U.S. Publication Nos. 2012/0310332 and 2012/029007.
Prior art valves generally include one or more leaflets that allow blood flow traveling towards the heart, but close to prevent blood flow traveling away from the heart. A problem with prior art implantable valves is that the valves create unnatural pressure build up during the complete restriction of blood flow traveling away from the heart. Unlike prior art prosthetic valves, natural valves are able to avoid pressure build up in the veins while still restricting undesirable volumes of fluid flow away from the heart.
The present invention solves this problem by providing a valve with two or more leaflets supported by a frame that form a central opening. The valve is deformable between a first position allowing fluid flow in a first direction through the central opening, and a second position restricting fluid flow in the second direction. While in the second position, the leaflets close the central opening. At least one of the leaflets includes a plurality of openings on the body of the leaflet. The plurality of openings allows minor fluid flow in the first and second direction in order to prevent undesirable pressure build up. Thus, valves of the invention allow fluid flow through the central opening of a first volume, and fluid flow through the plurality of openings of a second volume. The first volume is greater than the second volume. The amount of openings and the size of openings formed in a body of one or more valve leaflets can be chosen depending on the desired amount of fluid flow in both directions when the valve is in the restricted position.
As shown in
In the above embodiments, the amount of slack in the valve leaflet material determines, at least in part, how well the valve leaflets restrict retrograde flow and how large of an opening they permit during antegrade flow. In one embodiment, the valve prosthesis is configured such that, when the valve leaflets are positioned in their fully open position by antegrade flow, the cross sectional area available for fluid flow is between 90 and 10 percent of the cross sectional area of the expanded outer frame in the region of attachment of the valve leaflets to the support frame. In another embodiment, the valve prosthesis is configured such that the cross sectional area available for antegrade fluid flow is between 70 and 30 percent of the cross sectional area of the expanded outer frame in the region of attachment of the valve leaflets to the support frame. In yet another embodiment, the valve prosthesis is configured such that the cross sectional area available for antegrade fluid flow is between 50 and 40 percent of the cross sectional area of the expanded outer frame in the region of attachment of the valve leaflets to the support frame.
Elements shown in the embodiments described herein can be added to and/or exchanged with other embodiments to provide additional embodiments. It will also be understood that other valve body configurations are also contemplated as being within the scope of the present invention. For example, valves having four or more valve leaflets are contemplated. Hence, the number of leaflets possible for embodiments of the present invention can be one, two, three, four, five or any practical number. Bi-leaflet valves are preferred in low-flow venous situations. The valve leaflets may be of equal size and shape or of differing size and shape depending on the configuration of the supporting frame members.
The support frame used in the artificial valve prosthesis of the present invention can be, for example, formed from wire, cut from a section of cannula, molded or fabricated from a polymer, biomaterial, or composite material, or a combination thereof. The pattern (i.e., configuration of struts and cells) of the outer frame, including any anchoring portion(s), which is selected to provide radial expandability to the prosthesis is also not critical for an understanding of the invention. Any support frame is applicable for use with the claimed valve prosthesis so long as this structure allows the valve leaflets to be supported in the required position and allows the required portion of the perimeter of the leaflet to remain away from the vessel wall. Numerous examples of support structures are disclosed in U.S. Patent Publication No. 2004/01866558A1, published Sep. 23, 2004, the contents of which are incorporated herein by reference. In certain embodiments, the support frame includes one or more hooks to stabilize the support frame within the vessel, such as the hook 413 depicted in
References and citations to other documents, such as patents, patent applications, patent publications, journals, books, papers, web contents, have been made throughout this disclosure. All such documents are hereby incorporated herein by reference in their entirety for all purposes.
EQUIVALENTSThe invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting on the invention described herein. Scope of the invention is thus indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims
1. A system for endoluminal valve formation, the system comprising
- an elongate body defining a lumen and an exit port located on a side of the elongate body, wherein the side of the elongate body is configured to engage with a vessel wall;
- a tissue dissection probe disposed within the lumen, and configured to extend out of the exit port and into the vessel wall in order to form an intramural space in the vessel wall; and
- an imaging element located on the tissue dissection probe.
2. The system of claim 1, wherein the elongate body comprises a distal portion, and the tissue dissection probe is configured to distally extend out of the exit port in an orientation that is substantially parallel with the distal portion.
3. The system of claim 2, wherein a cross-section of the distal portion is smaller than a cross-section of the elongate body proximal to the distal portion.
4. The system of claim 1, wherein the tissue dissection probe defines a lumen terminating at a distal opening and is operably associated with a mechanism configured to deliver hydro-dissection fluid from the opening.
5. The system of claim 1, wherein the imaging element is selected from the group consisting of a photoacoustic transducer and an ultrasound transducer.
6. The system of claim 5, wherein the ultrasound transducer is an array-based transducer.
7. The system of claim 5, wherein the ultrasound transducer is a forward-looking transducer.
8. The system of claim 1, wherein the tissue dissection probe comprises an expandable member.
9. The system of claim 8, wherein the imaging element is disposed on the expandable member.
10. The system of claim 8, wherein the imaging element is disposed within the expandable member.
11. A catheter for endoluminal valve formation, the catheter comprising
- a catheter body defining a lumen and configured to enter a vessel;
- a distal portion of the catheter body configured to engage with a wall of the vessel;
- an exit port along a side of the catheter body and proximal to the distal portion; and
- a tissue dissection probe disposed within the catheter lumen and comprising an imaging element, wherein the tissue dissection probe is configured to distally extend out of the exit port and into a wall of the vessel.
12. The catheter of claim 11, wherein the tissue dissection probe is configured to distally extend out of the exit port in an orientation that is substantially parallel with the distal portion.
13. The catheter of claim 11, wherein a cross-section of the distal portion is smaller than a cross-section of the catheter body proximal to the distal portion.
14. The catheter of claim 11, wherein the tissue dissection probe defines a lumen terminating at a distal opening and is operably associated with a mechanism configured to deliver hydro-dissection fluid from the opening.
15. The catheter of claim 11, wherein the imaging element is selected from the group consisting of a photoacoustic transducer and an ultrasound transducer.
16. The catheter of claim 15, wherein the ultrasound transducer is an array-based transducer.
17. The catheter of claim 15, wherein the ultrasound transducer is a forward-looking transducer.
18. The catheter of claim 11, wherein the tissue dissection probe comprises an expandable member.
19. The catheter of claim 18, wherein the imaging element is disposed on the expandable member.
20. The catheter of claim 18, wherein the imaging element is disposed within the expandable member.
21. The catheter of claim 18, wherein the expandable member comprises a first end and a second end, and, when expanded, the first end defines a volume greater than the second end.
22. The catheter of claim 18, wherein the expandable member, when expanded, defines a conical volume.
23. A method for forming an endoluminal valve, the method comprising
- introducing a catheter into a lumen of a vessel;
- advancing the catheter to a location for endoluminal valve formation within the vessel;
- extending a tissue dissection probe from the catheter and into a wall of the vessel at the location; wherein the tissue dissection probe comprises a imaging element;
- forming, with the tissue dissection probe, an intramural space within the wall of the vessel, thereby forming a tissue flap; and
- imaging, with the tissue dissection probe, the forming step.
24. The method of claim 23, wherein the forming step comprises
- delivering hydro-dissection fluid from a distal end of the tissue dissection probe into the vessel wall.
25. The method of claim 23, wherein the forming step further comprises
- expanding an expandable member located on a portion of the tissue dissection probe disposed within the vessel wall.
26. The method of claim 23, wherein the imaging element is selected from the group consisting of a photoacoustic transducer and an ultrasound transducer.
Type: Application
Filed: Sep 19, 2014
Publication Date: Apr 23, 2015
Inventors: Jeremy Stigall (Carlsbad, CA), David Goodman (Carlsbad, CA)
Application Number: 14/491,383
International Classification: A61B 17/00 (20060101); A61B 17/22 (20060101); A61B 8/00 (20060101); A61B 5/00 (20060101); A61B 8/08 (20060101); A61B 8/12 (20060101);
